Air quality regulators have backed away from a proposal to ban use of a toxic chemical at two Southern California refineries, citing the potential loss of jobs and economic harm.

Instead, they are researching potential new safety measures to keep an accidental release of hydrofluoric acid from endangering people who live in densely populated neighborhoods in the refineries in Torrance and Wilmington.

Some residents have pressed for a ban on the chemical since the 2015 explosion at the Torrance Refinery. That blast came close to rupturing a tank holding tens of thousands of pounds of the substance. It is potentially dangerous because if it mixes with air at about 70 degrees, it can vaporize, creating a toxic ground-hugging cloud that can injure or kill those in its path.

Scientists and other staffers at the South Coast Air Quality Management District had been drafting a rule that would ban hydrofluoric acid from being used at the refineries in Torrance and Wilmington, the only two in California that use it. About 50 refineries nationwide use hydrofluoric acid or the modified form of it, including two in Texas and Wisconsin that experienced explosions in the past two weeks.

“I think a risk well-managed still might be a risk too great,” said Judith Mitchell, a Rolling Hills Estates City Council member who represents South Bay cities on the AQMD board. She said she prefers a phaseout. Manhattan, Redondo and Hermosa Beach city councils have also voted in favor of a ban on the chemical

But member of the AQMD board’s refinery committee stopped short of endorsing the ban proposal partly due to the expense and potential loss of jobs.

“Thus having a detrimental impact on local jobs, the price of gasoline and disrupting the business operations throughout the state,” said Larry McCallon, a Highland City Council member who represents Inland Empire cities.

Ending the use of hydrofluoric acid at the two refineries would have been an expensive undertaking, estimated to cost upwards of $600 million for each site.

Instead of a ban, the panel asked for the AQMD staff to research new safety measures.

The recommendation of the refinery committee is not binding. The full governing board of the South Coast Air Quality Management District would have to vote on any measures imposed on the refineries.